Sampling details, depth: The depths at which sampling should take place are as follows (in metres): 1, 5, 10, 15, 20, 25 (obligatory in the Kattegat and the Belt Sea), 30, 40, 50, 60, 70, 80, 90, 100, 125, 150, 175, 200, 225, 250, 300, and 400 metres, and as close to the bottom as possible (preferably less than 1 metre from the sediment surface to get near bottom oxygen concentration). For unstratified water less than 10m depth, samples will be taken from 1m or an integrated sample is taken. The regional conditions and circumstances have to be considered, when choosing the sampling depth.In EE 1, 5, 10 m and in the near bottom layer

Sampling details, replicas: At least two samples should be collected.

Method sampling: Samples are collected using a CTD system which is attached to a rosette sampler or a cast of reversing water samplers (e.g., Niskin or Nansen bottles) equipped with reversing thermometers.

Method of sample analysis: The determination of nutrients is based on colorimetric methods (c.f. Grasshoff et al., 1983, Kirkwood, 1996).

​QA/QC

​The quality system is formalized in the quality manual (Part B Annex B2 in the
HELCOM COMBINE manual). Guidance on the interpretation of ISO/IEC/EN 17025 'General Requirements for the Competence of Testing and Calibration of Laboratories' (formerly EN 45001 and ISO Guide 25) was given by a joint international EURACHEM/WELAC Working Group (EURACHEM/WELAC, 1992). Specific guidance to Analytical Quality Control for Water Analysis was elaborated by European - CEN/TC 230 (EN 14996) - as well as by international - ISO/TC 147 SC 7 (ISO/TR 13530) - standardization authorities.

The analytical requirements are specified, including definition of the type and nature of the sample and its environment, concentration range of interest and permissible tolerances in analytical error (Part B Annex B3 in the
HELCOM COMBINE manual).

It has been established, by laboratory studies, that the performance characteristics (selectivity, sensitivity, range, limit of detection and accuracy) of the method meet the specifications related to the intended use of the analytical results (Part B Annex B4 in the HELCOM COMBINE manual).

According to international standard, e.g. ISO 17025, a defined analytical quality has been achieved, maintained, and proven by documentation. The establishment of a system of control charts is a basic principle applied in this context. For further information for control charts refer to ISO/TR 13530 (1997). (Part B Annex B5 in the HELCOM COMBINE manual).

The comparability of the data has been ensured through an external quality assessment, such as participation in external quality schemes, ring text and/ or use of external experts (Part B Annex B6 in the HELCOM COMBINE manual).

​Frequency

​For assessment purposes, measurements should be made at least during the winter period (December-February)Mapping the winter pool of nutrients should be done a few times per year at set stations. High frequency cruise station sampling should be done >12 times per year (basically monthly sampling but weekly in the vegetative period) for d N and P. Ship-of-opportunity sampling frequency should be about every 200 m, and nutrients about every 10 km and every 1 - 3 weeks.

For ships-of-opportunity and helicopter sampling a single sample from the mixed surface layer can be taken.

​Spatial Scope

​Relation to D5 (eutrophication). Nutrients are measured in all HELCOM subbasins in the Baltic.

Method sampling: Water is continuously pumped through a system, taking water samples according to programming (Ferrybox sampling programme). The samples are stored in a dark refrigerator for max. 2 days.

Method of sample analysis: The determination of nutrients is based on colorimetric methods (c.f. Grasshoff et al., 1983, Kirkwood, 1996).

​QA/QC

​The quality system is formalized in the quality manual (Part B Annex B2 in the HELCOM COMBINE manual). Guidance on the interpretation of ISO/IEC/EN 17025 'General Requirements for the Competence of Testing and Calibration of Laboratories' (formerly EN 45001 and ISO Guide 25) was given by a joint international EURACHEM/WELAC Working Group (EURACHEM/WELAC, 1992). Specific guidance to Analytical Quality Control for Water Analysis was elaborated by European - CEN/TC 230 (EN 14996) - as well as by international - ISO/TC 147 SC 7 (ISO/TR 13530) - standardisation authorities.

The analytical requirements are specified, including definition of the type and nature of the sample and its environment, concentration range of interest and permissible tolerances in analytical error (Part B Annex B3 in the HELCOM COMBINE manual).

It has been established, by laboratory studies, that the performance characteristics (selectivity, sensitivity, range, limit of detection and accuracy) of the method meet the specifications related to the intended use of the analytical results (Part B Annex B4 in the HELCOM COMBINE manual).

According to international standard, e.g. ISO 17025, a defined analytical quality has been achieved, maintained, and proven by documentation. The establishment of a system of control charts is a basic principle applied in this context. For further information for control charts refer to ISO/TR 13530 (1997). (Part B Annex B5 in the HELCOM COMBINE manual)

The comparability of the data has been ensured through an external quality assessment, such as participation in external quality schemes, ring text and/ or use of external experts (Part B Annex B6 in the HELCOM COMBINE manual).

​Frequency

​Sampling is done between March – December, during the ice-free season. Samples are taken biweekly / monthly.

​Spatial Scope

All sub-basins.

​Spatial resolution

​Some tens of samples along the ship routes.

​

Monitoring requirements and gaps

Monitoring is to be carried out to fulfill assessment requirements of HELCOM ecological objectives that are specified through HELCOM core indicators. The requirements on monitoring can
include number of stations, the sampling frequency and replication.

​Monitoring requirements

For assessment purposes, at least 15 observations should be conducted during the period December-February made every winter in each assessment unit. The compilation of observations is expected to be distributed spatially within the assessment unit in a non-biased way.

​Gaps

Existing coordinated monitoring in some sub-basins does not provide sufficient temporal coverage to achieve high confidence in the core indicator status estimate (BSEP143) during the assessment season.

Monitoring should provide adequate data and information to enable the periodic assessment of environmental status, and distance from and progress towards GES as required by MSFD under Article 9 and 11.